Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.6.3.1 (NADPH oxidase)
 11,281 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Receptors for chemoattractants that direct the migration of phagocytic leukocytes to sites of injury/infection also modulate many other leukocyte functions that are critical to the inflammatory response. These chemoattractant receptors, members of the G protein-coupled heptahelical receptor family, have been classically linked to cell activation via phospholipase C, calcium, and protein kinase C. We show here that activation of the N-formyl peptide chemoattractant receptor stimulates an additional protein kinase C-independent pathway through the Src-related tyrosine kinase, Lyn, in human neutrophils. We demonstrate that activation of Lyn is associated with binding to the Shc adapter protein, which becomes phosphorylated on tyrosine residues. This interaction appears to be mediated via the Shc SH2 domain. Complexes of phosphorylated Lyn and Shc with phosphatidylinositol 3-kinase are rapidly formed in stimulated neutrophils, correlating with phosphatidylinositol 3,4,5-trisphosphate [corrected] formation and cell activation. This signaling pathway involving a Src-related kinase and the Shc adapter protein provides a potential mechanism linking chemoattractant receptors to downstream events involving Rac activation and NADPH oxidase. Regulation of Shc by G protein-coupled receptors may also allow these receptors to modulate the activity of the Ras/mitogen-activated protein kinase cascade.
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PMID:G protein-coupled chemoattractant receptors regulate Lyn tyrosine kinase.Shc adapter protein signaling complexes. 765 13

Reactive oxygen intermediates have been implicated in the transduction of TNFalpha signals, although the source of such oxidants has not been established. We found that activation of ECV-304 cells by TNFalpha was accompanied by a transient burst of oxidants and activation of JNK, both of which were suppressed by two distinct inhibitors of the phagocyte NADPH oxidase and the thiol antioxidant N-acetyl cysteine (NAC). We cloned partial and full-length cDNA sequences from ECV-304 cells and human umbilical vein endothelial cells (HUVEC), respectively, for p47(phox), demonstrating that these nonphagocytic cells express this adapter protein known to specifically initiate assembly of the NADPH oxidase in professional phagocytes. A mutant p47(phox), defective in the first Src homology 3 (SH3) domain (p47W(193)R), diminished JNK activation by TNFalpha. Surprisingly, p47(phox) resided entirely in the particulate, not cytosolic, fraction of cells. Immunostaining suggested partial colocalization with cytoskeletal elements, and cytoskeletal disrupters decreased both oxidant production and JNK activation by TNFalpha. A p47-GFP fusion protein localized to the cortical cytoskeleton in living cells; further, stimulation of cells with TNFalpha caused a marked concentration of p47-GFP in membrane ruffles, actin-rich structures associated with intense respiratory burst activity in stimulated neutrophils. We conclude that nonphagocytic cells express p47(phox), which appears to localize to the cytoskeleton and participate in TNFalpha signaling. We speculate that this physical targeting may prove important in conferring signal specificity and enhancing signaling efficiency of unstable oxidants.
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PMID:TNFalpha activates c-Jun amino terminal kinase through p47(phox). 1174 Aug 66

Activation of endothelial cell NF-kappaB by interleukin (IL)-1 constitutes an event critical to the progression of the innate immune response. In this context, oxidants have been associated with NF-kappaB activation, although the molecular source and mechanism of targeting have remained obscure. We found that RelA, essential for NF-kappaB activation by IL-1, was associated with the NADPH oxidase adapter protein p47(phox) in yeast two-hybrid, coprecipitation, and in vitro binding studies. RelA and p47-GFP also colocalized in endothelial cells in focal submembranous dorsoventral protrusions. Overexpression of p47(phox) synergized with IL-1beta in the activation of an artificial kappaB-luciferase reporter and specifically augmented IL-1beta-induced RelA transactivation activity. p47(phox) overexpression also greatly increased IL-1beta-stimulated RelA phosphorylation, whereas it had no effect on I-kappaB degradation or on RelA nuclear translocation or kappaB binding. The tandem SH3 domains of p47(phox) were found to associate with a proline-rich mid-region of RelA (RelA-PR) located between the Rel homology and transactivation domains. The RelA-PR peptide blocked interaction of p47(phox) and RelA, and ectopic expression of RelA-PR abrogated IL-1beta-induced transactivation of the NF-kappaB-dependent E-selectin promoter. Further, suppression of NADPH oxidase function through the inhibitor diphenylene iodonium, the superoxide dismutase mimetic Mn(III) tetrakis(4-benzoic acid)porphyrin (MnTBAP), or expression of a dominant interfering mutant of a separate NADPH oxidase subunit (p67(V204A)) decreased IL-1beta-induced E-selectin promoter activation, suggesting that p47(phox) facilitates NF-kappaB activation through linkage with the NADPH oxidase. IL-1beta rapidly increased tyrosine phosphorylation of IL-1 type I receptor-associated proteins, suggesting that oxidants may operate through inactivation of local protein-tyrosine phosphatases in the proximal IL-1beta signaling pathway leading to RelA activation.
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PMID:p47phox participates in activation of RelA in endothelial cells. 1261 29

The heterodimeric, integral membrane protein flavocytochrome b (Cyt b) is the catalytic core of the phagocyte NADPH oxidase and generates superoxide which plays a critical role in host defense. To better define the activation of superoxide production by this multisubunit enzyme complex, Cyt b-specific monoclonal antibodies (mAbs) and the p47phox SH3 domains (p47SH3AB) were used in the present study as probes to map surface structure and conformational dynamics in human neutrophil Cyt b. In pull-down and co-immunoprecipitation studies with detergent-solubilized Cyt b, the oxidase-inhibitory mAb CS9 was shown to share an overlapping binding site with p47SH3AB on the C-terminal region of the p22phox subunit. Similar studies demonstrated a surprising lack of overlap between the mAb 44.1 and CS9/p47SH3AB binding sites, and they indicated that the oxidase-inhibitory mAb NL7 binds a region physically separated from the p22phox C-terminal domain. Resonance energy transfer and size exclusion chromatography confirmed the above results for functionally reconstituted Cyt b and provided evidence that binding of both mAb CS9 and p47SH3AB altered the conformation of Cyt b. Further support that binding of the p47phox SH3 domains modulates the structure of Cyt b was obtained using a cell-free assay system where p47SH3AB enhanced superoxide production in the presence of a p67phox (1-212)-Rac1(Q61L) fusion protein. Taken together, this study further characterizes the structure of human neutrophil Cyt b in both detergent micelles and reconstituted membrane bilayers, and it provides evidence that the cytosolic regulatory subunit p47phox modulates the conformation of Cyt b (in addition to serving as an adapter protein) during oxidase activation.
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PMID:Characterization of surface structure and p47phox SH3 domain-mediated conformational changes for human neutrophil flavocytochrome b. 1800 84